The phenomenon is called "mobile blinders." Using a phone makes consumers blind to certain types of in-store come-ons. Hearst magazines has been particularly hard hit, WARC reports:

"We do find a number of people, if stalled for a minute, will steal a look at their email or news feed," David Carey, president of Hearst Magazines, told the FT. "Everyone that has products at checkouts has to battle for consumer attention," he added.

Hearst Magazines publishes 20 magazine titles in the USA, one of which, Cosmopolitan, recorded an 18.5% fall in single copy sales in the second half of 2012. Other magazines that saw double-digit falls in circulation included People and Star.